Rockin the Rockies

Rockin the Rockies
Stowe Mtn

Sunday, October 12, 2014

Another Pocket of Crystals at Lake George CO

As I'm writing this I have a pocket of crystals waiting on me up at Lake George. The site is fairly remote, so I'm not too worried about losing it to another prospector. The crystals are also not great so far, so the crystals can wait a day or two.
Clay covered pocket material

Handwashed amazonite...acid next!
 We were in an unprospected area, at least not dug in several years, so I thought Bob and I might have a chance of finding something good. White quartz was dribbling down the hill in various places, so I chose one area and followed the quartz up the hill. As I followed the quartz up the hill I picked up a broken crystal or two so I knew there was pegmatite producing crystals somewhere above me. As I climbed the hill the float or surface quartz diminished to almost nothing, so I started to take a real close look at the surrounding rock. One rock in particular caught my attention. The rock was firmly fixed in the ground (not roll down) and it had a lot of surface crystallization sometimes called "rice rock" due to the small formed crystals in the host rock appearing no bigger that grains of rice. I split this rock with me pick axe and pulled it out of the ground. I noted a few quartz shards underneath the rock, so I figured the host pegmatite was nearby if not directly underneath me, so I commenced digging. Right away I hit Zindwaldite.
Scraper pointing to plate of  Zindwaldite with amazonite beneath, note purplish color of pocket clay 
Now zindwaldite is not an accepted mineral term these days so lets just call it mica and move on. Mica is a sign of mineralization, so I continued digging. Soon I hit a piece of pegmatite that had quartz, cleavelandite and microcline. Using the spit field test method I noted the microcline was in reality amazonite though pale. I set my pick axe aside and moved to my rockhammer and scratcher. No sense in busting up crystals with my pick axe. I moved slowly at first, but determined everything I was finding was float and in fairly bad shape (cleaved) so I got more aggressive with my rock hammer til I hit better material. Soon I dug into some purplish clay and the number of crystal pieces increased so I assumed I was finally in the pocket.
Purple clay/dirt identifies pocket
Still the material was not of great quality. All the smokys were damaged and while the amazonites were okay they were only pale blue/green color. Expanding the dig I discovered a large area of mica. I decided to spend some time carefully taking out the fragile mica to see if I could salvage a piece for a geologist friend of mine, he seems somewhat concerned (from a scientific perspective) that I rifle through the mica without caring to save any.
Chunk of Zinwaldite/Mica
After I got the majority of the mica out I noted a fairly large number of well formed amazonite crystals behind the spot where the mica had formed. My theory is that the mica was a late-comer to the pocket and formed in the open areas of the pocket where space permitted. Perhaps wherever the mica formed in the pocket is an indicator of excess pocket room and a large enough void for better/larger amazonite crystals to form. So I guess my theory for this pocket is that mica means a large void, which means bigger and better crystals... time will tell. As it was getting time to go home I asked Bob to keep digging out the pocket while I wrapped what I had.
Bob found a nice crystal and let me know there was a lot of mica/
zindwaldite still deep in the pocket, so if my theory is right there should be a lot more crystals down there. Stay tuned for next weeks addendum to this report.

Second Vist: I returned to the pocket and dug it out. There were some new ice crystals, but they are tough to save this time of year ;-)
Little bit of snow today
I found a few well-formed amazonite specimens to add to my collection though the quartz crystals I found were very disappointing. I continued the dig until I was over 5 feet down and about 6 feet into the hillside.
Nearly 6 Feet down and done... time to fill it in
 In order to continue I would have to take nearly 6 feet of overburden down, or 6x4x2 feet of dirt and rock down and shovel it out to continue forward. One cubic yard of dirt weighs about 1ton. I’ve never had much luck with purplish sparkly mud that happened to envelop this particular pocket. I believe the purple indicates an infusion of manganese which has correlated to poor quality specimens for me in the past. I decided to discontinue the dig as the effort was not worth the prize as the pocket had narrowed down considerably from its original size of about 1ft high by 4ft across to about 6inches high by 10inches across. Maybe somebody in a few years will stumble across the dig and want to put the work into it and get a few crystals… not me.
Couple specimens in the back of the pocket for somebody else
So it’s time to find another pocket before the snow flies. Hopefully the next one will have better material.
I pulled out about 90 collectible specimens. Upon hand-washing some of the crystals I noted some fluorite clinging to the sides of the amazonite, so hopefully the crystals will clean up better and prove more interesting than first blush.
Cleaning is done: below are some of the amazonite crystals cleaned (best I can do). I tried a couple acids and a little bead blasting but you can only do so much. The amazonite were etched considerably by the fluorite in the pocket. The fluorite filled in some of the etched holes on the amazonite which makes the amazonite look dirty as well.
Largest amazonite here is about fist-size

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